1. Field of the Invention
The present invention generally relates to a method for measuring the maturity degree of a compost and a measuring solution, and deals more particularly with a method for measuring the maturity degree of a produced compost by compost manufacturers, distributors and users on site in a swift, easy and cost-effective manner, and a measuring solution.
2. Description of the Related Art
With recent growing environmental concerns in recycle-based society for efficient use of limited resources, the biomass (renewable organic resource) from animals and plants is focused and its use is demanded. In particular, by composting unused resources like livestock excreta and food waste, such processed materials will be reused as biomass resources in the recycle-based society.
Currently, Japan produces a large amount of livestock excreta exceeding 90 million ton a year. Under the circumstances, facilities for composting and recycling the livestock excreta are proactively established and introduced, as well as composting centers by individual agricultural areas to compost and recycle most of such livestock excreta.
Composting livestock excreta to produce mature materials is aimed at improving physical properties of the excreta by changing its ill-favored appearance, reducing odor and the degree of moisture content so that users can easily handle, as well as recycling it into biomass. Meanwhile, the biodegradation of easily decomposable organic matter such as proteins and sugars in a smaller volume, with no harm to crops if applied thereto, however, is strongly demanded to produce composts with no obstruction to germination or growth inhibition on crops.
Currently, environmentally friendly type of agriculture is proactively performed by a technology for treating and utilizing livestock excreta. Since composts from the livestock excreta are normally provided in an insufficiently, mature stage compost users cannot find reliability in such livestock excreta-derived composts, resulting in a limited use and shipment of product composts.
The immaturity in shipped product composts is caused by incomplete methods for measuring the maturity degree of a compost. Conventionally, the quality of product composts is empirically managed and assessed, mainly based on composting time required (period of time), compost's condition of color tone, odor, shape and texture, that allows for no specific, unified and precision-reliable approaches. It is particularly difficult to find the difference between a dried immature compost and mature compost from appearance.
As shown in the above descriptions, there are various types of techniques for assessing compost quality, thereby generating significantly different compost qualities among many composting centers and individual livestock farmers as compost manufacturers and providers. Thus, commercially available composts include immature composts.
Meanwhile, a use of immature composts and inappropriate treatment of livestock excreta can cause gas damage and nitrogen starvation by rapid decomposition in the soil and poor plant growth by a growth-inhibiting substance, resulting in significant adverse impacts on farm administration. Also, handling these materials can provide a source of zoonoses such as cryptosporidium (protozoan), pathogenic E. coli bacillus and salmonella. In addition to malodors, water pollution, due to eutrophication in closed water areas by the discharge of the zoonoses into rivers or nitrate nitrogen by their penetration into underground water, is a serious drawback in environmental conservation.
According to surveys by the Ministry of the Environment, many well water facilities that don't fulfill environmental water quality standards in nitrate nitrogen-containing underground water are found in agricultural and livestock areas. It is, therefore, suggested that excessive fertilizer application in agricultural land and inappropriate treatment of livestock excreta and domestic wastewater have significantly adverse impacts on the water quality of surrounding water areas.
The nitrate nitrogen in underground water or fresh vegetables can cause humans excessive consumption of nitrate, and particularly human infants and ruminants (like cows and bulls) methemoglobinemia (cyanosis), called as blue baby syndrome that impairs the ability to supply oxygen throughout the body with fatal impacts. Recently, the blue baby syndrome has become a big social issue, and its cases total more than 3,000 throughout the world.
The definition of full maturity is described as follows. Nutrients (easily decomposable organic matter) in raw materials are decomposed by aerobic microorganisms, and composted materials should be heated by heat of decomposition in windrow turning system at 55° C. for 2 weeks or more and in passive system at 55° C. for 3 days or more. The resulting mature composts will show no reheating, phytotoxicity, mixture of weed seed, or animal-and-plant pathogenic bacteria therein, ensuring product safety. Additionally, the process of full maturity is characterized by a rapid decline in ammonium nitrogen, slow increase in nitrate nitrogen and decline in total nitrogen. Nowadays, more and more consumers are concerned with food reliability and safety, and particularly with organic farming. In order to produce reliable agricultural crops for consumers, the importance of composting is currently realized in view of maintenance of soil fertility. There is a growing concern about resource-recycling agriculture to achieve recycle-based society, by using mature composts from livestock excreta, etc. In addition, farm households with advanced agricultural techniques are more interested in the use of full composts in farm production.
To establish resource-recycling agriculture in farming, particularly livestock and ackerland farming, the establishment of a system for supplying full mature composts is required. Though the maintenance of such a system needs a technique for measuring the maturity degree of a compost, such a technique (a.k.a. quality management method) has not been established. Currently, public research organizations study and develop methods for measuring the maturity degree of a compost in a more objective manner.
Specifically, such methods include chemical property analysis, seedling test, easier and quicker germination test, seed-pack root elongation test, use of seedling culture apparatus, methylene blue colorimetric method, Analysis of amino acid by paper chromatography, E. coli culture test, a method for chemically measuring nitrogen, phosphorus, potassium, pH and EC in the compost, a method for BOD (Biochemical Oxygen Demand) in the compost (compotester), liquid chromatography method and far-infrared ray method.
Among other things, the method for measuring the maturity degree of a product compost according to its temperature is disclosed in a research result, “Simple Evaluation and Use of the Quality and Components in Compost from Livestock Excreta (Garbage-derived Compost)” conducted by National Agriculture and Food Research Organization and National Agricultural Research Center.
This study focused on fluctuations of temperature in the composting process. More specifically, after a product compost is heated up to 60° C. or more, and as the compost is repeatedly turned, the temperature gradually declines, approaches and corresponds closely to outside air temperature. Then, the compost can be determined to be full mature. Thus, using the fluctuations of temperature data in a product compost, its maturity completion can be determined, and this decision can be made only by measuring the temperature.
Also, methylene blue calorimetric method is disclosed as a relatively easy method for measuring the maturity degree of a compost. In this method, after a solvent is added to a weighed compost sample and stirred, it is filtered and a reaction reagent containing a methylene blue pigment is added thereto. By incubating it in a thermostatic chamber at 35° C. for 24 hours and estimating dissolved oxygen (DO) amount consumed due to the biodegradation of organic matter, the maturity degree of a compost can be determined.